Section 3(d) reads as below:
“the mere discovery of a new form of a known substance which does not result in increased efficacy of that substance or the mere discovery of any new property or new use for a known substance or of the mere use of a known process, machine or apparatus unless such process results in a new product or employs at least one new reactant.
Explanation: For the purposes of this clause, salts, esters, ethers, polymorphs, metabolites, pure form, particle size, isomers, mixtures of isomers, complexes, combinations and other derivatives of known substance shall be considered to be the same substance, unless they differ significantly in properties with regard to efficacy.”
In essence, section 3(d) aims to prevent a phenomenon commonly referred to as “ever-greening”. The underlying assumption is that derivatives, such as salt forms, polymorphs, isomers etc that are structurally similar to known pharmaceutical substances are likely to be functionally equivalent as well–and if this is not the case and the new form of an existing substance works better than the old form, it is up-to the patent applicant to demonstrate this and claim a patent.
To this extent, section 3(d) draws a distinction between “evergreening” and incremental innovation. By making derivates with added efficacy patentable, section 3(d) encourages sequential developments of existing products or technologies that help bring in improved products to the market.
Now, in Roche vs CIPLA, the earlier known substance is Gefatinib. Roche then claims a structurally similar compound, Erlotinib. The question essentially is: is Erlotinib a derivative of Gefatinib? If it is a “derivative”, then under the explanation to section 3(d), unless such
derivative demonstrates “a significant difference in property with regard to efficacy”, it will be construed as the “same substance” as Gefatinib. It appears that even if
As a colleague of mine who wishes to remain anonymous and whom I deeply respect for his knowledge on both the Indian pharmaceutical industry and patent law writes and tells me:
“Structurally, they both have the common 4-quinazolinamine nucleus but the substitution patterns are quite different. They both are derivatives of 4-quinazolinamine, but are not really derivatives of each other (though it could be tenuously argued that any two compounds that have even the slightest of similarities could be interconverted.)
Such an argument could then be reduced ad absurdum to say that only one compound in any series of compounds having some structural similarity and acting by the same mchansim whould e patentable. That’ll truly be absurd. It should also be noted that (a) erlotinib has an additional indication (combination with gemcitabine for pancreatic cancer) and (b) erlotinib ha it is own NCE exclusivity in the USA which shows that the FDA considered it to have a different active moiety from gefitinib which was marketed earlier.”
I tend to agree with him. A compound that has some amount structural similarity with a prior compound cannot always be treated as it’s “derivative”. If this were always the case, then a large number of pharma compounds could be said to be “carbon” derivatives of some sort and therefore subject to section 3(d)!! Note in particular his last sentence which suggests that even if Erlotinib were treated as a derivative of Gefatinib (marketed as Iressa and a patent over which was recently rejected in India), then it is likely that since it has an additional use (pancreatic cancer) over and above Gefatinib, it ought to be able to fulfill the condition of “enhanced efficacy” under section 3(d).